Convert PDF to Vector AI file.

As Milenium said, you simply open the PDF in Illustrator.

However, Canva is bitmap only. Therefore, Illustator will treat it as an image, not a vector graphic.

Illustrator has an Image Trace command that might work for you. You may or may not be satisfied with the results, depending on the image.

I don't use Canva so I don't know what templates you are referring to.

Whether you are using Canva or Canva Pro, the exports are pixel based (even though you are getting a pdf). Depending on the structure of the logo, you might try Image Trace - you might get a good outcome. But most likely will need a lot of clean up. Starting from scratch is the most likely outcome.

I've never used Canva Pro but with a quick Google search I found that it appears to only export files as jpegs or pngs. Both of those formats are raster formats (pixel based). There is no magic formula to change those files to vector art in Illustrator. Yes, Illustrator does have an Image Trace feature which can make raster images into vector but the results are extremely erratic in terms of accuracy. Also, the resulting vector file is a mass of compound paths and masks which can be difficult to edit even for experienced users. If your end result is a vector file that can be comfortably edited in illustrator then it is best to actually create it in Illustrator.

You simply open the PDF in AI. If there's any editable data it will be converted automatically and be available for further treatment, if not and it's all just lumps of pixel data then it would be pointless. The "multiple templates" are likely just different pages converted to artboards, but it's really not clear what you mean since you have not provided screenshots. Most users here won't know much about a service that seems to be a glorified online version of Powerpoint for business presentations by non-designers. Either way, I would suggest you at least start by reading the online help for illustrator to alleviate soem of your confusion and perhaps learn a bit of the lingo and AI's capabilities...

Mylenium