@Dayeon_Lee sure.
I used Djangosaml2idp(IDP) as a separate system to configure any service provider (SP) that I need to integrate with it.
then I enable (SP) for OpenEdx then I integrated it with Djangosaml2idp.
at the following, more details about OpenEdx SP SAML may help you.
After that, I did manipulate at login code in Openedx to redirect users to login by Djangosaml2idp rather than Openedx login. That will help you to login 2 systems (Djangosaml2idp and Openedx)at the same time, which is will help you later to go to any other system (Sps) by Djangosaml2idp.
To summarize, At following step about how users navigate between systems:
1- go Openedx site, then press the login link.
2- redirect users to Djangosaml2idp site, the login.
3- redirect users again to the Openedx site.
4- then users can go to any other (Sps) systems if is it configured at Djangosaml2idp.
hopefully, it is clear.