In order to use the Password Depot Add-on in Firefox you first need to install it properly. Thus, you need to open the following link in the Firefox browser:
Afterwards, you should be able to see the below browser window:
Please also check if you have installed the latest update of Firefox. You can check this in your browser's menu under Help -> About Firefox.
If you have done all this and are still getting the message "Only with Firefox - Download Firefox now" which is always getting displayed even though you have downloaded Firefox again and again, it seems like you have installed a special edition of Firefox which the Password Depot Add-on is not compatible with.
If you do observe this problem, please proceed as follows:
First it is necessary to delete your current installation of Firefox. Afterwards, please download the latest version and install it on your computer. As soon as the installation has been completed successfully, open Firefox and start all over again as described above for adding the Add-On to your browser.
If the Password Depot Add-on could be added to Firefox correctly you should have this view in your browser:
The Password Depot icon in blue should now also be displayed in your browser on top on the right:
Hint: Please note that the Add-on is only working if both Password Depot as well as the correct database where the corresponding entry is saved to are available. Otherwise, auto-complete of your data won't be possible at all.