The raspberry has an arm processor (holy crap but it really seems to be able to do 64 bit calculations 
impressive this model 3) afaik the command set of arm processors are different from the ones in a ‘standard computer’ (RISC vs. CISC architecture)
so you could try to compile it from source for yourself but you most certainly cannot use the precompiled x86/x64 binaries on an arm processor 
Oh and I just realized you did use the v0. 8.1
You should go with the newer version of the browser mentioned in the last dev update (yes that should ideally be linked on the homepage - but I’m sure @SarahPentland and @dugcampbell are keeping an eye on this for the new homepage that is in the making right now)