SDL Trados Studio 2021 SR1 CU3 - says I need administrator right? (I do)

When trying to install this new update I get the message:

"The installer has insufficient privileges to access this directory: C:\\Program Files (x86)\SDL\SDL Trados Studio\Studio16. The installation cannot continue. Log on as administrator or contact your sytem administrator."

I am the administrator (and only profile on this laptop) - any ideas what I can change to resolve this?