Here’s my Okta and PSU config -

When I hit PSU, it loads the Okta login, I mfa, then when it tries to load the PSU page I get this error:
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c3f1430d4a90fb07af2040a202c687a53d888f5a.png
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I restarted the PSU service and now it works
I dont use Okta myself, but hopefully these might help:
Okta SAML - 404 page - PowerShell Universal - Ironman Software Forums
OpenID Connect | PowerShell Universal
OpenID Connect | PowerShell Universal
I tried to manually add the info as in the first link, the other two are oidc so not applicable here.
Doesn’t work.
I cannot see your metadata but have you tried matching your ACS and Callback? Generally, callback is ACS. Do you have SAML trace? Firefox supports SAML tracer which can be helpful.
I restarted the PSU service and now it works