Polylang with custom header

Hello,

I need to translate this website: [ redundant link removed ] and I would like to use Polylang.
The website is built with OceanWP and Elementor. The header and footer are customised. Two questions come into my mind:

1. Does Polylang work well with the above theme?
2. How can I show the possibility to change languages?

Thanks for your help!

The page I need help with: [log in to see the link]