Cannot sign into Adobe Sign application on Samsung Note5

I currently have an Adobe subscription that includes the full Adobe Document Cloud software (i.e., Adobe Acrobat Pro, Adobe Fill & Sign, etc.). However, while I can sign into the Adobe Sign dashboard on a computer, I cannot log in to the Adobe Sign mobile app (and stay logged in) on my Samsung Note5. It's worth mentioning that I can sign into (and keep signed into) the Adobe Fill & Sign mobile app without any issues.

What would be the reason for not being about to sign into the Adobe Sign app?