trying to run excel (Office 2016) crashes...is this because need to buy license?

happy to pay for licence so I can gt this working i.e. Open office applications sandboxed but I cannot find anywhere to buy it..just says it is free to use but page https://www.sandboxie.com/RegisterSandboxie does not seem to have anywhere to pay 

 

from FAQ 

Office Suites (Libre Office, OpenOffice) (Support for MS Office 2016/Office365 is offered for the paid version)