offloaded whatsapp not installing back

i needed to free space so I offloaded my whatsapp business . Unfortunately, now when I tap the WhatsApp Icon on my phone, a white screen with a web image sign shows on my phone , ie it won't open.

How can I fix this without losing all my chats.

When looking in settings in Iphone storage, it shows documents and data and app size, and gives me the option to Offload App, rather than Reinstall App. And if I go into the AppStore it shows Open for Whatsapp and if I click on it, it brings up the same white screen with small whatsapp sign.

Can someone please help.