I agree with @GrowerGoneWild … I had always better results with dome (for about 5-7 days then usually gradually remove the dome) than without. But it depends what air humidity do you have in grow room… In my dry conditions it was too dry in my eyes (clones wilted)…
But as it was suggested, it can properly work without …
90% RH is OK I think… you could also raise temp because I think it roots better in warm temps…
I’d say choice of dome and choice of rooting hormone (for cloning: powder or liquid) are totally subjective things… Try and experiment little bit and go with what works for you best.
There is also great cloning step by step guide by @metaphysical