I get a message saying “Either Steam isn’t running or you don’t have a suitable license”

Solution – the VC 2013 and 2010 Redist is required and installed by Steam. It appears yours may be corrupt. Please download here:

https://www.microsoft.com/en-us/download/details.aspx?id=40784
https://www.microsoft.com/en-gb/download/details.aspx?id=13523