Are you trying to do a new install of Web Services or an upgrade?
Also, are you on 18.0, 18.2 or 18.3 for Dynamics GP, because depending on which version, dictates the requirements for installing Web Services as mentioned in this blog:
community.dynamics.com/.../loader-error-when-attempting-to-install-web-services-for-microsoft-dynamics-gp-the-security-object-does-not-exist-key-25cc1a21-2cc4-4b13-a1c8-eea186fb688a
We frequently see access denied messages when you had a previous install of Web Services, so objects are present in the GP databases, but the security store and/or Azman information isn't on the server you're installing onto, because you've moved to a new server for Web Services.
As well, when installing Web Services, make sure you're a local administrator on the server you're installing Web Services onto as well as a domain user account. You'll also need to have permissions on the SQL Server as well when you run the Configuration Wizard for Web Services.
The only other thing I'd mention is, if you're actually on GP 2018, i.e. 18.0.xxxx, you don't need the KB4527536 patch, that patch is only required for 18.2 and 18.3, as well as if you're on 18.3 for GP, you must be using the MDGPFALL2020_DVD_ENUS media to install Web Services from. This DVD already has the KB4527536 patch built in, whereas the 18.2 DVD doesn't, so you must slip-stream the patch, also mentioned in the above blog.
Thanks,
