Annalisa Mantovani 

Does this KB article shed light on the issue?
Access Management 9.6 - "The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters" error when validating the SAML2P Identity Provider (sdl.com)

Seems that you are using a company specific login system or a VPN.

Yes, I am using a company specific login system, not a VPN today. Yesterday, it was perfectly working with VPN, which I often use when I work from home.

Also, I have no rights whatsoever to make any changes/install/uninstall, only the IT manager is allowed. 

Annalisa Mantovani 

This problem is with the certificate that is required for login. 
I don't know if it is related to your company's login system or to RWS who just had login problems to Language Cloud services. These problems have been solved a while ago.
It might be worth trying again (maybe restart your laptop) to find out whether it was related to this or whether you need to check with your IT.

I am referring to these 2 emails from RWS:

Emails received, thanks. I can access the Trados Cloud Platform on the browser, so I fear the issue is related to my company's login system.

I have already restarted my laptop 3 times this morning, yet the error persists when opening Trados locally.

Emails received, thanks. I can access the Trados Cloud Platform on the browser, so I fear the issue is related to my company's login system.

I have already restarted my laptop 3 times this morning, yet the error persists when opening Trados locally.

Annalisa Mantovani 

Annalisa Mantovani said:

I fear the issue is related to my company's login system.

Have you found the resolution to your problem?