User research for vast database product releated to IOT

I was asked to work on UI and UX part of an existing IOT web based application which is related to database.

It is very vast product and I can't try and test this product due to some confidential things. The product database is very huge and company has provided me with read-only credentials. In short I am unable to understand how functionality works.

I need to do user research (I am new in user research) and find pain points. On basis of this I have to provide ideas of improvement.

In order to do the improvements in current UI/UX I have to understand the product first. But I am unable to understand it because I don't have full access of this product.

So in this case how should I start my work? How do I start in this condition?

Please help.

Thank you in advance!