Speed->Caching->Dynamic caching tab->Click on the Broomstick icon (located towards the bottom right..." data-socialbacklinks="1" />
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When installing a new site manually on Siteground 

Go to SiteTools->Speed->Caching->Dynamic caching tab->Click on the Broomstick icon (located towards the bottom right part of the page)

Once flushed you should then be able to run the installation.

https://prnt.sc/10w2zvn