The tutorial instructs to install gtk-vnc.tcz which is not available in the 6.x repo but in the 4.x repo.
wfcmgr.bin seems to be the main executable, started from ~/.X.d/launch_ica (which doesn't need to me made executable, btw). The command right after that one is sudo poweroff so no wonder it shuts down immediately after boot since you don't have wfcmgr.bin anywhere.
wfcmgr.bin might have been removed from Citrix Receiver or was renamed.
The link from the tutorial to download Citrix Receiver is not valid so no way to know what version the creator of the tutorial used.
I'd suggest you search for another, more up to date tutorial, and better yet, first try to get familiar with Tiny Core in general.