Convert text to Date

please try 

YearMonth_Date = DATE(
YEAR(DATEVALUE("01-" & RIGHT(Table[YearMonth], 2) & "-" & LEFT(Table[YearMonth], 4))),
MONTH(DATEVALUE("01-" & RIGHT(Table[YearMonth], 2) & "-" & LEFT(Table[YearMonth], 4))),
1
)

U can simply change text to date format in PQ if that does not work. There are also plenty of solutions to this question online. Please google before posting.
See for instance:
Solved: Converting text year to date in Power Query - Microsoft Power BI Community
Solved: Convert string to date - Microsoft Power BI Community
Solved: Converting from Text to Date - Microsoft Power BI Community

There are loads more online.
"Text to date Power BI"

Could you give more of an explanation please? You already have activate date, then Year Month that i'm assuming comes from activate date. It look like you're trying to recreate activate date? I'm not sure what you're trying to do. 

Could you give an example output. You may need to use CONVERT() to turn your string into a date format. Let me know and i'll get straight back to you 🙂 good luck

How about Month_hoa convert to Date (just show month number)?

hi JennyMilf 

what do you get with this:

YearMonth_Date = DATE(LEFT(Table[YearMonth], 4), RIGHT(Table[YearMonth], 2), 1)

?