Here's the recommended MINIMUM PSU power requirements for the RX 570:
25A on the 12V rail.
1x6 pin PCI-E power connector.
Check that the PSU complies with all those requirements and you should be fine running that GPU on it. Always remember to buy known brands, not cheap, unknown ones, as they tend to lie in their specs and to use bad quality components. And always try to buy an 80 Plus PSU, that also adds quality to the build.