Is login via POST still possible?

Hey there,

I don’t know if this is the right category so feel free to direct me to another category that’s more fitting.
So we are planning out the infrastructure of our (newly founded) company right now and we want to use Nextcloud as a sharing platform with our customers.
My superiors want our customers to be able to login with their credentials via a form on the company website and then be redirected to their Nextcloud folder.
So I did some research and the method of choice is probably POST. - But is it still working on Nextcloud 17/18 since the plugin hasn’t been updated on github since 2017?
Or is there any other solution that allows our customers to login via a form on our company website which transfers the login information to our Nextcloud server?

Thanks in advance!