SPLA cannot be enabled due to limited list of Data Centers in Regional Acronis DC. Some of the DCs are missing in the list.
The list of available DCs has been updated since versions 3.0.5 and 3.5 of Acronis Cyber Infrastructure.
You can type your data center address manually, if it is not available in the list.
Log in as a Partner Admin, type in the DC address and activate the SPLA.
Should you face any difficulties: log in via different web browser and try again.