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Hey, may you try to do this:

Before you click on download, go to the 3 points at the right top of your browser, then search the option  "desktop site" this will change the whole page as you were using in a PC, them try to download again.
Like thisChange to desktop mode on your mobile browser

And if this don't work, try to turn on the option "download from unknown source". 

Like this> How to Install Apps from Unknown Sources in Android