Unfortunately not. A purchase that was not opened from the WeWard app cannot be rewarded, even with an invoice.
To reward a purchase, the brand needs to know it came from WeWard. Tapping "Shop on" from the app's Top Deals page is what links the purchase to your account. Without that tap, the brand pays no reward and we cannot credit it in its place. In-store purchases are not eligible either.
Next time: open the Top Deals page in WeWard, choose the brand, read its conditions, then tap "Shop on" before ordering, and accept the cookies on the brand's website.
Full step-by-step: How do I shop with your partners and get rewarded?