@ekarim2020 , Yes the user who is running the flow is the site collection administrator.
Also,I have custom solutions uploaded at SIte collection level and I am using them to create subsite under same site collection with custom template.
I am using different url to crate subsite, /_api/web/webinfos/add with Post and getting error like
"File or arguments not valid for site template '{3B27D009-DE90-4ABF-A743-F6EB71ED08B6}#SITE TEMPLATE - ospWind - 20180917-200p' or Access Token Not Found
Also one more issue, some of the my solutions are not visible under create subsite option, Any idea why this happens?
Please help.
Thanks