2nd Opinion and advice for marketing and lead conversion on a Recruitment based website using Google Ads

We have a website [login to view URL] that advertises for multi drop delivery driver jobs on either the main recruitment page [login to view URL] or one of the localised pages [login to view URL] [login to view URL] [login to view URL] [login to view URL] [login to view URL] A potential candidate will see our advert and follow the advert link, from there they can complete a small application form which then generates the lead for interview. We've invested 000's into the advertising budget and now the actual lead conversion of people visiting the site and completing the application form is now minimal and it is having an impact on business. I'd like a second opinion and potential improvements if any can be found on how to increase the volume of people applying for the job.