If you have no taxes to pay or credits that you are eligible for, then it’s likely you don’t need to file a tax return. However, it would be a good idea to contact the CRA to confirm. If you are in Canada or the United States, you can call 1-800-959-8281. If you are somewhere else you can call 613-940-8495. Here are more ways to contact the CRA: https://www.canada.ca/en/revenue-agency/corporate/contact-information/telephone-numbers.html
I also received a NR4 from my bank in Canada. I'm a non-resident living over seas. In the NR4 form is has Income code 61 (interest is from a GIC). No tax was deducted (Exemption Code S). My bank always tell me to contact a charter accountant when ask questions. So I called CRA. CRA said I don't have to pay any tax or file any tax return form (don't have to do anything). But it still scares me every year I get an NR4 in the mail.