Managed server that does not allow SSH public key authentication

One of our clients is using a managed dedicated server (without root access) for hosting their web applications (quite high frequented websites, all on the same server but that's another topic).

We sometimes have to upload some data on that machine and have an user to log in over ssh - with a password.

I requested to set up public key auth for our account to at least have some baseline security standard. Turns out the provider does not support …

access account applications auth authentication clients cybersecurity data hardware high hosting key log machine managed password public public key root root access security security standard server ssh standard support web web applications websites