Gradcracker focus on stem graduates - they are good but maybe not for HR. External companies often take care of grad recruitment - so don't limit yourself to only apply directly to firms.
University careers services are variable. But they are underused and so any approach from grads is met with enthusiasm. They run all sorts of programs from expert panels, careers cafes, leading industry figures lectures. Careers workshops. Application help.
In my experience grads spread themselves far too thinly (the opinion of our contact at Gradcracker too) they apply to countless companies, don't tailor their applications and get rejected at first glance. You are better doing 5 excellent tailored applications than 100 ok generic applications. Get Grammarly to pick up on typos in all communications including Linkedin and Whatsapp. Know how to write a letter or note using appropriate spacing and paragraphs...it's amazing how many grads do not know the difference between writing a handwritten letter and a typed letter.
Know what industry you are applying to and talk about why it excites and interests you, read up on current industry and company news. Respond to all communications promptly. If they give you an online test to complete - do not wait till the last minute to do it.
Be human and relaxed in interviews, you are trying to connect with someone - the days of excessive formality have gone, have good questions to ask - there are loads available online so be careful you aren't sounding like a cliche, have good examples prepared in advance to talk about, don't make these up - unless you are a good liar, it's really obvious. And don't suggest that getting through University during Covid makes you special and particularly resilient - everyone else had to do the same and they aren't making a big deal about it. Don't be scared of your weaknesses - know them, be able to talk about them and know how to address them.
There are more grad opportunities this year than usual - she has an excellent chance of getting in if she applies herself as seriously to the job hunt as she did to her studies - every job advert is an exam question - there's a list of things they want - answer each one, demonstrate you have it or how you hope to develop it.
The big drive traditionally starts in October but loads of companies recruit year round - so don't wait till October - if anything start applying now - it's good practice and hopefully she'll get some good feedback and hone her approach for success.