hello dogeeze, please never install anything that you haven't requested yourself just because a popup tells you so.

there might already be some sort of malware present on your pc when such popups appear. therefore i'd suggest to go to firefox > addons > extensions & to remove any suspicious entries (toolbars, things that you have not installed intentionally, don't know what purpose they serve, etc).
also go to the windows control panel / programs and remove all toolbars or potentially unwanted software from there.
finally, run a full scan of your system with different security tools like the free version of malwarebytes & adwcleaner.

Troubleshoot Firefox issues caused by malware

I also had Motive, and was never able to find out what it is or where it came from. There is a web site with that name. I think they collect web data or some such. You should also check your plug-ins. I found Motive there as well. If you do a search of your hard drive, you may find several Motive folders. What I did was to rename all the motive folders. The Motive extensions were still there, so I disabled them. After I Reset Firefox during an unrelated problem, Motive was gone.

I hope this helps.