There are a few different types of pop-ups and overlays that impact SEO in different ways. The RiQ widget is not considered a pop-up, it is classed as an overlay, which has the least impact (if any) on SEO.
Google and other search engines also look at aspects such as how easily the modal can be closed, and if the modal is interactive or a static window with sales information. Our widget is able to be closed easily, is interactive, and has what Google calls 'workability', meaning that it has a function rather than just being a display ad that pops up.
The only way that the widget would impact your SEO is if the content you have in the widget is 'advertising heavy', such as 'call us for 25% off your next holiday' rather than 'call us to book your holiday', for example.
We're very proud of the relationships we've built with our customers, and regularly engage in discussion with their SEO and digital marketing teams. So far, we've never been provided with any proof by a client that we've negatively affected their SEO.
For a more detailed explanation on how modals and pop-ups can impact your SEO, check out this article by Moz.