License applied to the Site Recovery Manager solution is "Site Recovery Manager Standard".
When attempting to protect more than 75 VMs on a site, in Site Recovery, the following error is seen: “There are not enough licenses installed to perform the operation.”
VMware Live Site Recovery 9.x
The "Site Recovery Manager Standard" license is limited to protect only 75 VMs per site:
Thus attempting to protect more than 75 VMs per site will fail stating there are not enough licenses.
Reference documentation for "Site Recovery Manager Standard" license - VMware Site Recovery Manager Licensing.
To protect more than 75 VMs per site, the below options are available:
Create another site pair between the two vCenters and split the license (with less than or equal to 75 VMs per license) across them.
Assign a "Site Recovery Manager Enterprise" license.
Else, assign the new subscription based VMware Live Recovery license.