Non-donor: https://maven.aristois.net/bundle/1.19.3.zip?type=fabric&launcher=multimc
Donor (will not work if you're not a donor): https://maven.aristois.net/bundle/1.19.3.zip?type=fabric&launcher=multimc&donor=true
Download the zip and then place the files where they need to go. Probably somewhere such as:
EMC.jar - PolyMC/instances/(instance that has fabric installed)/mods/
1.19.3 folder - PolyMC/instances/(same instance)/libraries/EMC/
(For different MC version just change the URL)