Can I still PCS from AIT with an acute fracture in my ankle and an MRC3 profile?

Possible, but you are probably going to have better odds of staying put until your medical condition improves and then PCS. Best bet to get the most accurate answer is to speak with your Medical Provider that you're seeing at your AIT and speak with your Cadre.

TRADOC 350-6
H-6. Disposition of Soldiers with injuries or illnesses that prevent continued training
a. Report IET Trainee/Soldiers that miss three or more consecutive full days of training, due to
illness or injury, in ATRRS as a medical hold reason code. Trainee/Soldiers will remain coded as "medical holdovers" until they have recovered from their illness/injury, or for as long as they remain on a profile. Once the profile has expired, and the Trainee/Soldier resumes training, remove the medical hold code in ATRRS.
H-6 b. (3) (a) Medical professionals should advise commanders when a Soldier is determined to not meet the minimum requirements as described in paragraph H-5b and H-5c. The advice should clearly articulate whether the Soldier has received adequate treatment and rehabilitation or should
be medically separated from the Army. Medical professionals will document physical status on the DA Form 3349. Commanders will instruct medical holdover status for Soldiers with a DA Form 3349 to remain on active duty status until the Soldier has been declared fit for further training/permanent change of station, or until they are medically separated from the Army.

Depends on where from, I’m currently at Fort Jackson and we aren’t allowed to start out processing while on profile