In general we would highly recommend taking a look at the example scenes and scripts that come with the spine-unity runtime, and referring to the spine-unity documentation page, as these are always up to date and not potentially incorrect and outdated as any thirdparty videos on youtube.
Unfortunately it did not for me and when I tried to enter the code manually I don't think Unity liked it.
Please also note that you have a spelling mistake as you named your method
.._Complate instead of
.._Complete, so if you manually spelled
AnimationEntry_Complete correctly it for sure will not find that method.
In general always resolve any compile errors from top to bottom of the list, in your case an error in line 42 might have caused follow-up problems (also of auto-completion) in the lines below.