From where I can download UIM 8.5.1 and When is the EOS/EOL ?
The 8.51 installer are no longer available for download.
These and earlier ones were removed after the Purchase of CA by Broadcom.
You will need to open a support request to get access to this as approval will have to be given by management.
Important Note: EOS for UIM 8.5.1 is October 31, 2020