Hi,
Currently someone needs to invite you to a project on Mendix portal. Very often the access will be still available even if the person left the organisation and someone need to manyally revoke the access.
Rather, if we implement a SSO kind of access with an AD group. Those who need access to the project will be added to the company AD which will propogate to project access, the moment an associate left, he would be removed anyhow from the AD Groups and same should be populated to Mendix project access.
Think about this to implement.