In the case when you will use the Search feature on the login page, you have to specify the search engine link. Option is available in WebAdmin / WHITE LABELING / Login page option / Search
The exact format of the search engine query is provider specific.
Here are a few examples for search queries where some search provider accept query with "#q=%%query%%" and one with "?q=%%query%%"
- google.com - https://www.google.com/#q=%%query%%
- bing.com - https://bing.com/#q=%%query%%
- duckduckgo.com - https://duckduckgo.com/?q=%%query%%
- qwant.com - https://qwant.com/?q=%%query%%