I heard that Freemake Video Converter is unsafe to run, as it has adware. Is this true or is it safe?
No, it's not true. The application is safe to be installed, but you have to be very careful when installing because it's bundled with adware. Download the setup package, then proceed to normal installation and always choose CUSTOM. Uncheck any offers that are displayed through the installation process and that's it.
I have checked the package on VirusTotal and it appears it only has adware: https://www.virustotal.com/en/file/65ebed41dac4f88b80c0092f85387981bc8a03029715010b55a1f8b92e069d46/analysis/1441097350/