Commentary for Arakhin 5:6

ממשכנין אותן (exact pledges from them) – the treasurer enters into their homes and takes it against their will.

With regard to those who made a vow of value: they take a pledge from them.
With regard to those obligated to bring a hatat or asham: they do not take a pledge.
With regard to those obligated to bring an olah or a shelamim: they do take a pledge.
And even though he is not atoned for unless he is willing [to pay his obligation], as it is said: “willingly” (Leviticus 1:3), they coerce him until he says: I agree.
The same is true in the case of divorce documents: they coerce him until he says: I agree.
This famous mishnah deals with how a court enforces a person to pay various obligations.
Section one: If someone makes a vow of value (or worth) and is late in paying his debt, the court can take a pledge (an object of value) from him in order to force him to pay his debt.
Section two: However, if someone has transgressed and is obligated to bring either a hatat (sin offering) or an asham (guilt offering) and he is late in bringing it, the court does not take a pledge from him. The general rule is that if the obligated item comes to atone for a sin, the court does not take a pledge.
Section three: If the person vowed to bring an olah (a burnt offering) or a shelamim (an offering of well-being) the court does take a pledge, because these are not sacrifices that atone for sin.
Section four: This and especially the next section are famous because they deal in general with the ability of the court to enforce obligations. The Torah states that an olah must be brought willingly. If so, how can the court force him to bring an olah or shelamim? The answer is that they force him to say that he agrees. Even though he clearly does not want to bring the sacrifice, the fact that he verbalizes his desire to do so is sufficient. Similarly, when it comes to divorce, the court can force him to write out a divorce document. As we know from other sources, a man can only divorce his wife willingly, but we know that under many circumstances the court forces him to divorce his wife (see for instance Ketubot 7:10; see also Gittin 9:8). Again, how can something be enforced and yet still be done willingly on the part of the person being coerced? The answer is that the court forces him to say that he agrees to the divorce. And as we learn in Gittin, this enforcing can be done even through physical coercion.
The Rambam, in his commentary on this mishnah, notes that although it seems that when the person says, “I agree” he doesn’t really mean it, we attribute to him that he does have the correct intention because he is doing what he should have done of his own free will. According to the Rambam, it is as if his evil urge not to perform the correct act overcame him, and by force the court makes him do what his good side really wanted to do in the first place. We should recognize that this is a dangerous principle and could be broadly applied to many categories. However, the Mishnah does not turn this into a blanket rule, but rather only mentions it in reference to these two categories sacrifices and divorce.

חייבי חטאות ואשמות – since it is for atonement that came, they do not procrastinate [in providing the sin-offering or guilt offering] , and they do not exact pledges from them. But the sin-offering of the Nazirite, since it does not come for atonement, and does not prevent him from drinking wine, for since the blood of one of the sacrifices was sprinkled, the Nazirite is permitted to drink wine and to become defiled to the dead, on occasion that he acted negligently and delayed, therefore we exact the pledge on his sin-offering.

חייבי עולות ושלמים – even though the burnt-offering atones for [violation of] a positive commandment and for a prohibition that after its violation is transformed into a positive commandment, since the negative commandment is not an obligation, it is not considered as an atonement and one can delay performing it, therefore, we exact a pledge from them. But there are those liable for burnt-offerings where we don’t exact a pledge from them, as for example the burnt-offering of a leper, because it delays his purification and it does not come to delay him.

כופין אותו עד שיאמר רוצה אני – where that the Jewish court exacts a pledge from him, he must state: “I want to do it.”

וכן אתה אומר בגטי נשים – whomever his judgement is that they force him to divorce [his wife], the Jewish court of Israel beats him until he says: “I want [to do it] (i.e., divorce his wife), and he gives [her] the Jewish bill of divorce and it is appropriate (see also Tractate Ketubot, Chapter 7, Mishnah 10).