You need to understand a few things about this
(here's a more helpful link)
https://www.rferl.org/a/nationalists-mark-75th-anniversary-of-ukrainian-insurgent-army/28794861.html
Firstly Ukraine has a long history of subjugation by the USSR (the real USSR, as opposed to the rather pathetic imitation EUSSR that some people bang on about :-) ) and many of the commemorations of the resistance to that sadly do draw far right elements. This is a facet of Eastern Europe which is by no means peculiar to Ukraine, but also seen in countries like Hungary, Poland and most of all Russia.
Politically these groups in Ukraine are non-starters, with zero representation in parliament.
Second, if you compare the OP's link, and similar links, with mine here, you may get the suspicion that there is a bit of an agenda there by the relevant Kremlin sponsored news agencies, who want you to believe that Ukraine is a hotbed of Fascism that threatens Europe when in reality the threat to the west comes from the sponsors themselves. Ultimately, this is a nationalist resistance commemoration, and while there is never anything good about people giving Nazi salutes, it is not exactly the Nuremburg rallies.