But to use openflow you might need a license. Please check the below article:
I think it is supported. OpenFlow is supported on the following platforms:Summit X440, X430, X460, X460-G2, X480, X670, X670-G2, and X770 series switches
BlackDiamond 8900 (XL-series) and C-series with single Management module only
Below articles will provide you more idea on how to install virtual exos:
It looks to be platform limitation on X620.
Please find the below article for more information: