The ongoing law requiring a negative coronavirus test to enter private licensed accommodation (and hotels) has now been update by the government of the Canary Islands.
Previously all tourists entering hotels and holiday villas needed a negative test, but now the law has been update to allow accommodation providers to accept proof of vaccination and recent Covid-19 recovery too.
Since 24th May, British travellers have been able to enter Spain without a negative test. However, it has been the case that those checking-in to Canarian hotels and villas have needed a test in order to access their accommodation.
Remember, this is a local - not national - law and enforced at the accommodation (not the border as you enter Spain).
The tourist board of the Canary Islands website says you can side-step the testing requirement if you
"Have an official accredited document that shows that you have been fully vaccinated in the eight months prior to your trip or have received at least one dose of a COVID-19 vaccine authorised by the European Medicines Agency (EMA) within the past four months and at least 15 days prior to your trip. The official accredited document of vaccination must state the vaccine received, the number of doses and the date on which each dose was inoculated.
Can prove with an official medical certificate or public document that you have had and recovered from the disease within the past 6 months."
If the above don't apply to you, an antigen test is acceptable. The lateral flow antigen tests provide much quicker results and are much cheaper.
Check more details with your accommadation provider.
More information here: Covid-19 in Lanzarote