I have yet to find a solution for this. I did discover that checking the box for createAccountWithEntReq should allow for this functionality, I did not previously have this checked, but I still can’t figure out how to correctly reference the entitlements in the Create Account body with this checked.
Web Services Documentation and ‘createAccountWithEntReq’:
https://community.sailpoint.com/t5/IdentityNow-Connectors/Web-Services-Source-Configuration-Reference-Guide/ta-p/78511?_ga=2.215463583.9072797.1685457148-174873549.1684948098&_gl=1*x4k2iq*_ga*MTc0ODczNTQ5LjE2ODQ5NDgwOTg.*_ga_SS72Z4HXJM*MTY4NTQ1NzE0OC4zNy4xLjE2ODU0NTgyMzMuNC4wLjA.#accountRequest